The invention relates to an amplifier circuit comprising first and second transistors of like conductivity type with the emitter of the first transistor connected to the collector of the second transistor, the transistors being arranged with their main current paths in series in a voltage sharing configuration between first and second supply terminals for a voltage supply, means for d.c. biasing the base of said first transistor for setting the quiescent voltage at the connection between the first and second transistors, means for applying an input signal comprising relatively high and low frequency components to the second transistors and means for deriving an output signal from a load connected between the collector of the first transistor and the first supply terminal.
Amplifier circuits of the above type usually obtain the d.c. bias for the base of the first transistor from the collector of that transistor which means that an a.c. component is applied to that base. This results in both transistors amplifying both the high and low frequency components. Alternately, the base of the first transistor may be separately d.c. biased with this base being decoupled for all amplifier signal frequencies which would produce the same result.